21 
Some Bacterial Diseases oe Plants. 
the soil that has washed clown a hillside back up onto the shallow 
places of the farm. If this is done, one should be very certain that 
the hillside from which this soil has washed is free from all plant 
diseases, for the writer is familiar with several instances where in¬ 
fection has been spread over healthy land in this way. 
Where no remedy can be given, it is clear that our only hope of 
controlling a disease is by preventing its spread. By observing the 
foregoing suggestions, it is believed that the most serious plant dis¬ 
turbances can be prevented to a great extent, or at least controlled. 
BACTERIOSIS OF BEANS. 
Frequently the foliage, stems and pods of the common beans, 
as well as the Lima bean, are preyed upon by a bacterial disease, 
Pseudomonas phaseoli (Smith), known as Bacteriosis. The symp¬ 
toms are such as to make it readily distinguishable from all other 
maladies to which the bean is heir. 
There appear on the different parts of the plant, especially on 
the leaves, large, watery, brown patches or blisters that soon dry up 
and cause the tissue to become brittle and to curl, leaving the foliage 
ragged and good for nothing. The pods seem to furnish the best 
food supply for the microbes and it is here that we find the disease 
at its best. Small discolored spots appear at first, whicn spread very 
rapidly and produce large lesions with pink or reddish brown bor¬ 
ders, and which have pale yellow or amber colored crusts over the af¬ 
fected areas. This crust is due to the accumulation of myriads of 
amber colored bacteria which have formed a layer over the broken 
down tissue. After a time the pod rots and the beans are worthless. 
Warm, wet weather seems to favor the disease, for the germs 
grow best under these conditions, and the beans at this time produce 
succulent growths, which are more readily attacked. Rain and dew 
are doubtless agents in spreading the germs from one part of the 
plant to another by washing them from old lesions onto unaffected 
parts. Insects play an important part in disseminating the trouble, 
consequently any measures which tend to check these pests will aid 
in controlling bacteriosis. The distribution of the disease is further 
effected by dead vines and leaves carried on the wind; by the soil, 
and through the seed. New land which has never grown beans 
seems to be freer from the disease than old, and should always be 
used when available. 
The seed used in planting should be selected by hand and all 
the lighter ones discarded, since experiments show that diseased 
seeds are less dense than sound ones. As yet no satisfactory method 
has been found which can be recommended for treating the seed to 
destroy the causal microbe which does not lower the viability of the 
seed. 
